Abstract We0081: Role of Leiomodin 1 in Hypoxic Neovessel Maturation

Peripheral artery disease (PAD) is a complex cardiovascular disease affecting >230 million people worldwide. Phenome-wide association study (PheWAS) have linked genetic variations within Leiomodin 1 ( LMOD1 ), a gene preferentially expressed in smooth muscle cells (SMCs), with PAD. Although, this finding suggests a novel association between LMOD1 and PAD, the contribution and mechanism by which this gene promotes the pathogenesis of PAD remains to be identified. To determine whether LMOD1 -PAD association is independent of atherosclerosis and is a result of a separate angiogenesis related mechanism, we subjected mice to hindlimb ischemia, an established model of PAD and found that compared to wild-type control mice, non-atherosclerotic Lmod1 heterozygous ( Lmod1 -/+ ) mice displayed impaired blood perfusion. Furthermore, micro-CT and vessel permeability assays demonstrated this phenotype to be a potential consequence of fewer neovessels and increased vessel permeability, suggesting reduced Lmod1 may impair the formation of mature neovessels. Interestingly, in vitro hypoxic assays revealed the observed in vivo defects to be a result of impaired SMC: 1. Proliferation; 2. Migration and 3. Recruitment to neovessels when co-cultured with control endothelial cells. In keeping with these findings, our RNA-sequencing studies identified TNFα Induced Protein 3 ( TNFAIP3 ), a TNFA downstream target gene known to attenuate SMC migration and proliferation, is induced in cultured LMOD1 deficient hypoxic human SMCs. Moreover, our new preliminary molecular signaling studies revealed this increase in TNFAIP3 expression to be a consequence of dysregulated Cbp/p300 interacting transactivator with Glu/Asp rich carboxy-terminal domain 2 (CITED2)-Hypoxia Inducible Factor 1 subunit alpha (HIF1A) signaling pathway. Finally, simultaneous LMOD1 and TNFAIP3 in vitro knockdown studies revealed rescue of SMC migration, indicate the proposed mechanism is reversible. Together, these findings reveal that reduced LMOD1 promotes the pathogenesis of PAD via TNFAIP3 mediated defects in the formation of mature neovessels.